The invention concerns an infinitely variable friction gear.
Such infinitely variable friction gears usually have situated, coaxially to a common shaft input and output disks, mutually arranged in pairs and having their inner surface toroidally shaped, the same as friction wheels disposed between the pairs of input and output disks. The friction wheels are in frictional contact both with the input disks and the output disks and transmit by frictional contact to the output disk the torque transmitted to them by the input disk, the rotational speed of the friction wheels being higher the distance between their contact points and the input disk and axis of rotation. The rotational speed of the output disks, on the other hand, is higher the nearer the contact point between friction wheel and output disk lies on the axis of rotation. Consequently, by the swinging of the friction wheels, the rotational speed of the output disks can be infinitely variably and arbitrarily adjusted. For this purpose, the axes of rotation of the friction wheels are supported on a carrier controllable via a swinging device.
The basic principle of such an infinitely variable friction gear has already been described in U.S. Pat. No. 2,152,796 published in the year 1939. In this publication are provided two pairs of concave input and output disks between which tiltably supported friction wheels are disposed so that a torque transmitted via an input shaft to the input disks and the friction wheels, depending on the relative position of the friction wheels with a reduction ratio dependent thereon, is fed via the output disks, a gear step and a hollow shaft to a summarizing gear in the form of a planetary gear. The web of the planetary gear drives an output shaft connected with the input gears such as a motor vehicle. The output shaft can be disposed parallel to the input shaft and spaced therefrom. The output gear and both output disks are pivoted on a sleeve which rests by its ends on bearing brackets. The arrangement of the gearing brackets, respectively, between one input and output disk presupposes a sufficiently large space between the disks.
The gear according to U.S. Pat. No. 3,739,658 also has a pull-and push variator with two input and output disks disposed in pairs between which are placed pivotally supported friction wheels. This construction includes a bearing bracket which is a component part of the housing and is spatially situated horizontally between the two output disks. The power flowing out of the output disks is fed to a hollow shaft, via a planetary gear, that also acts as differential. The hollow shaft is non-rotatably retained by ball bearings in the bearing bracket.
The output gear is in driving connection with a gear which is non-rotatably fastened on the housing of a torque converter. The latter drives the output shaft of the gear. The arrangement of the torque converter at the entrance of the output shaft implies a relatively large axial space between input and output shafts of the gear. This extensively limits the utilization of the gear, since the required installation space is not always available.
U.S. Pat. No. 4,893,517 has disclosed an infinitely variable friction gear having one input shaft which penetrates in a housing. The housing is divided by means of a partition wall in two cavities in each of which are supported one input disk and opposite to it one output disk with friction wheels therebetween, wherein both the input disk and the output disk lie in both cavities upon a common axis relative to which the friction wheels can swing to achieve the desired speed ratio. Both pairs of input disks and output disks are situated in the cavities with mirror symmetry to each other in a manner such that both output disks lie side by side and this at both sides of the partition wall that divides the two cavities from each other and in which is supported one gear which is actuated by the two output disks jointly with the output torque.
The problem to be solved by this invention is to reduce the construction expenditure of such an infinitely variable gear and to lower the production cost.
The invention solves the stated problem in a generic infinitely variable friction gear.
The advantages achievable by the invention consist in the use of considerably less stationary and movable parts.
The invention is explained with reference to the drawings which shows: